Poseidon and Hera's plan

Hera was livid. Her divine essence seethed with an incandescent fury that threatened to shake the very foundations of Olympus itself. The unthinkable had happened—the Greeks had lost the Trojan War. 

It felt like a waking nightmare, a cruel jest woven by the Fates themselves. How could such a thing be possible? The Greeks had been the stronger force, their army vast and composed of the finest warriors to ever walk the earth. More than that, they had been led by the greatest of their kind—mighty kings and warriors who had carved their names into history with blood and steel. 

Agamemnon, the High King, had been slain. Menelaus, who had sought vengeance for his stolen wife, lay dead. Ajax, the indomitable warrior, had fallen. Even Heracles, the son of Zeus himself, had perished. It was inconceivable.